Greater London · England
North Finchley Sand Mastic
Sand mastic in North Finchley from a team with over 20 years’ experience. 180+ five-star Google reviews and a 4.9 rating.
- Mastic that needs renewing before redecorating
- Gaps between timber frames and stone or brick
- Old sand mastic that has cracked, crumbled or fallen out
Sand mastic in North Finchley
Sand mastic has long been used to fill the joint between timber frames and masonry. It’s made from sand and a linseed-oil-based binder and built up by hand. On older homes, it suits the building far better than silicone. We work on stone surrounds, timber door frames and tenement windows, and people most often call us about old sand mastic that has cracked, crumbled or fallen out and a silicone bead on a sash window that spoils the look.
London’s Victorian and Edwardian terraces were built with timber sash windows, and many still have them or their replacements. Whatever is in the opening now, the joint between frame and wall is what keeps the weather out.
Every job is covered by a one-year guarantee.
- Location
- North Finchley (N12, N20, N11)
- Wider area
- Greater London
- Cover
- A year, on every job
- Quote
- A clear quote up front
- Phone
- 0345 464 0079
- Page updated
- 26 October 2026
What we can’t put right
We will not take on work that will not last, so these are the limits:
- Sashes that need overhauling
- Putty and glazing repairs
- Planning or listed building consent (your local planning authority decides)
If in doubt, call 0345 464 0079 or drop us an email and we’ll say what we think.
Surfaces we seal
- Stone surrounds
- Sash and case windows
- Period & listed homes
- Tenement windows
- Timber door frames
- Brick reveals
What happens on the day
Our applicators work methodically: protection first, then preparation, sealing and a tidy-up. Typically it takes anything from a few hours to a full day, depending on how many windows. Many London jobs are in flats, so we come ready for stairs, narrow hallways and shared entrances. If the building has a concierge, managing agent or access rules, tell us when you book.
- We look at the surrounds with you and agree the joints to renew.
- We remove the old, loose mastic.
- Deep gaps are packed so the mastic sits at the right depth.
- We apply the mastic by hand and shape it.
- The surface is finished to suit the stone or brick.
Before we arrive
- Mention any tricky access
- Let us know about earlier repairs to the joints
- Tell us if parking is tricky
Get a quote
For a quote, ring 0345 464 0079 or email us and tell us where the job is and what the problem looks like. We’ll send you a clear quote before any work starts.
Advice
How the job changes by surface
Sash and case windows
A sash window’s box frame sits in the masonry opening. The gap round it is pointed with sand mastic.
Stone surrounds
Stone surrounds suit sand mastic well. It finishes to look like part of the surround.
How to look after the new joints
To keep the joints looking good and working properly:
- Ask us before painting near the mastic
- Find out about consent before window work on a listed home
- Look over the window mastic once a year
- Avoid patching sand mastic with silicone
Look at the mastic when you look over the windows. Small cracks are easier to deal with early.
Fine cracks show the mastic is starting to fail. It’s easier to renew it before it drops out.
Your questions about sand mastic in North Finchley
Is parking an issue for sand mastic in North Finchley?
In much of London, parking needs planning: a visitor permit or a bay close to the door helps a lot.
Can you help a landlord with a rental near New Southgate station?
Yes. We work for letting agents and landlords as well as homeowners. Just ring 0345 464 0079 or send us an email with the address and what needs doing, and we’ll give you a clear quote.
Do you work in North Finchley?
Yes. From our base in Crawley, we cover South East England, London and all of Scotland, and that includes North Finchley.
Can you seal over the old sealant?
No, and we never do. It can look neat for a few weeks, but the new layer lifts away from the old one. Removing the old sealant completely is the only lasting way.
What should I tell you?
A short description and the location, plus pictures if you have them. We’ll ask anything else we need to know.
Will there be a smell?
Some sealants have a smell while they cure, which fades as it sets. Ventilation helps.
When will the new mastic be hard?
It skins over fairly quickly but takes longer to harden fully. We will explain what to expect before we leave.
What is sand mastic?
Sand mastic is a traditional material for pointing round windows and doors. It combines sand with a linseed-oil-based binder.
Landlords, agents and businesses in North Finchley
Failed sealant is one of the commonest items on a check-out report, and it’s quick to put right between tenancies. We can quote for more than one property at once.
Businesses can book us for washrooms, kitchens, offices and more. For commercial premises, we can talk through working times when we quote.
Signs you need sand mastic in North Finchley
Decorating can disturb tired mastic. It’s often found when windows are being prepared for paint.
The problems people normally mention when they call include:
- Gaps where the frame meets the masonry
- Cracked mastic round a front door frame
- A silicone bead on a sash window that spoils the look
- Wind and rain getting in round a sash window
Letting a property close to New Southgate station? Then cracked sand mastic around sash windows lets in the draughts tenants complain about.
Questions to ask before you book
- How much experience the applicator has
- Whether they’re fully insured
- What preparation is included
- What guarantee comes with the work
Nearby places to North Finchley
What else we do in North Finchley
North Finchley homes and the weather
The South East is one of the drier parts of the UK, yet outdoor joints still have to be sealed dry, so jobs are booked with the weather in mind. In a converted house or block, who looks after the windows depends on the lease, so check that before you book.
For an older house near a landmark such as St. Barnabas Church, the joint between an old wall and a newer frame is usually the first place rain gets in. If you look after a building such as Sacks Morasha Jewish Primary School, its window and door frames need their mastic kept sound, just like a home’s.
North Finchley is about 1 mile north of Finchley, in Greater London. Every kind of property in North Finchley is covered for sand mastic, old or new, large or small. Every job comes with our 12-month guarantee. North Finchley is one of 764 places in Greater London where we work for sand mastic. We also work in London, about 9 miles from North Finchley.
We cover every part of the N12, N20 and N11 postcode area for sand mastic and the streets around it. You’ll find streets such as High Road, Lodge Lane and Percy Road, all of which we cover. North Finchley sits on or near the A1000, which makes travel easy. We also cover the places around North Finchley: Woodside Park (1 mile west), Oakleigh Park (1 mile north), Whetstone (1 mile north), Friern Barnet (1 mile east) and Finchley (1 mile south). We also work in nearby towns such as London (9 miles south-east), City of Westminster (7 miles south), Marylebone (7 miles south), Kensington (8 miles south), St Pancras (7 miles south) and Shoreditch (8 miles south-east).
Landmarks near North Finchley
Locally, jobs take us to homes and businesses close to Friary Park, Woodhouse College and The Bohemia pub, among other places. Nearby too are Francis Skaryna Belarusian Library and Museum (0.5 miles west) and St Michael's Catholic Grammar School (under half a mile south-west). The closest station to North Finchley is New Southgate station, roughly 1.4 miles east of the centre. Well-known places in the area include Finchley Memorial Hospital (0.8 miles south) and Francis Skaryna Belarusian Library and Museum (0.5 miles west). Green spaces nearby include Darland's Lake and Glebelands Local Nature Reserve.
How we quote for sand mastic
Your quote is based on your job. We look at:
- Mould in or behind the old joints
- The number and length of the joints
- The type of sealant required
- How many rooms, windows or areas are involved
We don’t show prices on the website, because the cost depends so much on the job itself. For a quick quote, please call 0345 464 0079 or drop us an email.
Helping us quote
What to tell us when you ask for a quote:
- The address or postcode of the job
- Roughly how big the job is
- If someone has resealed it before
- The type of property
Quotes start with a quick conversation. Tell us what’s wrong, where it is and how much there is, and we’ll talk you through what we’d do. When it suits you, phone 0345 464 0079 or drop us an email.